A safety control circuit and control method

Abstract

The application discloses a kind of safety control circuit and control method, and first inherent type failsafe circuit controls first power switch on-off according to the differential gate enable signal input;Second inherent type failsafe circuit controls relay contact according to the differential gate enable signal after signal conversion input, door opening signal, door lock state, the state of first inherent type failsafe circuit first power switch, unlock circuit state and its own state, and input encoding signal to unlock circuit;Unlock circuit controls second power switch to open according to the differential gate enable signal after signal conversion input, door opening signal and door lock state, according to the signal after encoding sent by second inherent type failsafe circuit, realizes safety unlocking.Under the condition of reaching high safety level, still have good reliability, avoid similar device series use, the influence of common cause failure mechanism to actual safety.

Description

TECHNICAL FIELD

[0001] The present application relates to rail transit door control technology, in particular to a safety control circuit and control method. BACKGROUND

[0002] Both rail transit vehicle doors and platform doors have safety requirements for avoiding unintended door opening. The electrical safety of door opening is determined by the control of the door lock, so that unintended unlocking can be avoided by safety control of the door lock, thereby realizing the safety of door opening. The prerequisite for door unlocking is to give an enabling hard-wire signal control with a safety level by the upper control system. The door enabling signal is valid, and the software of the door control unit gives a software unlocking instruction according to the door logic if the door needs to be opened. At this time, the door can be unlocked, and then the door drive mechanism is controlled to open the door. Otherwise, even if the door control unit software incorrectly issues an unlocking instruction, the door lock cannot be unlocked due to the lack of the prerequisite for unlocking. Therefore, the door lock needs to be controlled by an independent inherent fault safety circuit. The safety level is generally measured by SIL (safety integrity level), and the higher the SIL level, the lower the probability of unintended door opening. The prior art generally uses a door enabling hard-wire signal to control an electromagnetic relay coil, and the contacts control the power supply of the door lock control circuit or device. One relay can achieve SIL2, and when a higher safety level is required, multiple relay coils and contacts are used in series.

[0003] Problems and shortcomings of the prior art:

[0004] ① The electromagnetic relay itself has a failure rate, and the reliability of the circuit is low after multiple relays are used in series.

[0005] ② The circuit is connected in series by devices of the same type, and similar devices have similar failure modes, so there may be a common cause failure mechanism that reduces the actual safety. SUMMARY

[0006] The purpose of the present application is to provide a safety control circuit and control method that has good reliability under the condition of meeting safety requirements, avoids the use of similar devices in series, and avoids the influence of the common cause failure mechanism on the actual safety.

[0007] Technical solution: A safety control circuit according to the present application comprises: a first inherent fault safety circuit, a second inherent fault safety circuit, and an unlocking circuit, wherein:

[0008] The input of the first inherent safety circuit is a differential door enable signal, which controls the first power switch. The input terminal of the first power switch is connected to the positive pole POW+ of the door lock power supply, and the output terminal is connected to the positive pole of the unlocking circuit. The state of the first power switch is fed back to the control terminal of the second inherent safety circuit and the door lock unlocking circuit.

[0009] The input of the second inherent safety circuit includes the differential door enable signal after signal conversion, the door opening signal, the door lock state, the state of the first power switch of the first inherent safety circuit, the state of the unlocking circuit, and the state of the second inherent safety circuit. The output state of the first power switch of the first inherent safety circuit, the state of the unlocking circuit, and the state of the second inherent safety circuit are sent to the unlocking circuit through an alternating signal encoder. The second inherent safety circuit controls a relay contact, which is connected to the low side of the door lock and the negative pole POW- of the door lock power supply.

[0010] The input of the unlocking circuit includes the differential door enable signal after signal conversion, the door opening signal, and the door lock state. According to the encoded output state of the first inherent safety circuit, the state of the unlocking circuit, and the state of the second inherent safety circuit sent by the second inherent safety circuit, the unlocking control signal is outputted to control the second power switch to be turned on, realizing safe unlocking.

[0011] Optionally, the first inherent safety circuit includes a PWM controller, a voltage conversion circuit, a rectifier filter circuit, and a first power switch. The input of the PWM controller is a differential door enable signal, and the output is a gate drive signal of the first power switch through the voltage conversion circuit and the rectifier filter circuit. The source of the first power switch is connected to the unlocking circuit, and the drain of the first power switch is connected to the positive pole POW+ of the door lock power supply. The state of the first power switch is fed back to the second inherent safety circuit as the output state of the first inherent safety circuit.

[0012] Optionally, the first inherent safety circuit further includes a discharge circuit, which is arranged at the gate of the first power switch. After the door enable signal fails, the voltage across the gate of the first power switch is discharged, so that the drain-source of the first power switch is cut off.

[0013] Optionally, the second inherent safety circuit comprises a hardware logic controller, an isolation circuit, a relay, and a power-off delay circuit, the input of the hardware logic controller comprises the signal-converted differential door enable signal, the door opening signal, the door lock state, the output state of the first inherent safety circuit, the state of the unlocking circuit, and the state of the relay, one output of the hardware logic controller is connected with the unlocking circuit, the other output is connected with the isolation circuit, the other end of the isolation circuit is connected with the relay, the relay is connected in parallel with the power-off delay circuit, the other end of the relay is connected with the door lock low side and controls the communication between the door lock low side and the negative pole POW- of the door lock power supply, and the state of the relay is fed back to the hardware logic controller as the output state of the second inherent safety circuit.

[0014] Optionally, the isolation circuit comprises a fifth resistor and a second optocoupler, the relay comprises a relay coil and a relay normally open contact, the first port of the second optocoupler is connected with the hardware logic controller through the fifth resistor, the second port is connected with GND, the third port is connected with the door enable N signal, and the fourth port is connected with the relay coil low side; the relay coil high side is connected with the door enable P signal, the relay normally open contact is connected with the door lock low side, and when the relay coil is powered, the relay normally open contact is closed, and the door lock low side is connected with the negative pole POW- of the door lock power supply.

[0015] Optionally, the unlocking circuit comprises a CPU, a second power switch isolation circuit, a driving circuit, and a second power switch, the input of the CPU comprises the signal-converted differential door enable signal, the door opening signal, the door lock state, the output state of the first power switch of the first inherent safety circuit numbered, the state of the unlocking circuit, and the state of the relay contact of the second inherent safety circuit, the output of the CPU is connected with the second power switch isolation circuit, the other end of the second power switch isolation circuit is connected with the driving circuit, the driving circuit is connected with the gate and the source of the second power switch, the source of the second power switch is connected with the first inherent safety circuit, the drain of the second power switch is connected with the door lock high side, and the state of the second power switch is fed back to the second inherent safety circuit as the state of the unlocking circuit.

[0016] Optionally, the second power switch isolation circuit comprises a fourth resistor and a first optocoupler, the driving circuit comprises a second resistor and a third resistor, the first port of the first optocoupler is connected with the CPU through the fourth resistor, the second port is connected with GND, the third port is connected with one end of the third resistor of the driving circuit, and the fourth port is connected with the negative pole POW- of the door lock power supply.

[0017] One end of the second resistor of the driving circuit is connected with the gate of the second power switch, the other end is connected with the source of the second power switch, and the other end of the third resistor is connected with the gate of the second power switch.

[0018] Optionally, the door lock power supply adopts a completely independent isolated power supply, forming an independent power supply loop from POW+ to POW-, and the first power switch, the second power switch and the relay in the loop adopt MOSFET, IGBT or triode.

[0019] Based on the same inventive concept, a safety control circuit control method of the present application comprises the following steps:

[0020] The positive end P and the negative end N of the differential door enable signal are input into the first inherent safety circuit, the second inherent safety circuit and the unlocking circuit;

[0021] The first inherent safety circuit modulates, transforms and rectifies and filters the differential door enable signal, and outputs the rectified and filtered signal, which drives the first power switch to be turned on, connects the positive pole POW+ of the door lock power supply, and feeds back the output state of the first inherent safety circuit to the second inherent safety circuit;

[0022] The second inherent safety circuit encodes the output state of the first inherent safety circuit, the state of the unlocking circuit and its own state into an alternating signal and sends it to the unlocking circuit through a hardware logic controller; at the same time, the second inherent safety circuit performs logic control on the differential door enable signal after signal conversion, the door opening signal, the door lock state, the output state of the first inherent safety circuit, the state of the unlocking circuit and its own state, and drives the low side of the door lock and the negative pole POW- of the door lock power supply to be connected through optical coupling isolation;

[0023] The unlocking circuit performs logic control on the encoded output state of the first inherent safety circuit, the state of the unlocking circuit and the output state of the second inherent safety circuit, and the received differential door enable signal after signal conversion, the door opening signal and the door lock state, and outputs an unlocking controller signal, which controls the high side of the door lock and the positive pole POW+ of the door lock power supply to be connected after optical coupling isolation; and then realizes the unlocking of the door lock after power supply;

[0024] After the differential door enable signal is invalid, the high side of the door lock and the positive pole POW+ of the door lock power supply are disconnected, the low side of the door lock and the negative pole POW- of the door lock power supply are disconnected with a time delay, and the door lock is in a non-electric locking state.

[0025] Further, the control method is specifically:

[0026] The differential door enable signal drives the PWM controller to output a pulse signal, the pulse signal drives the isolation transformer to output a pulse signal, and the pulse signal output by the transformer is rectified and filtered to obtain a gate drive signal of the first power switch, which in turn controls the first power switch to be turned on, and realizes the connection between the source of the first power switch and the positive pole POW+ of the door lock power supply;

[0027] Synchronously, the differential gate enable signal is input to the hardware logic controller after signal conversion, the hardware logic controller processes the differential signal after signal conversion, and outputs a control signal to the input end of the isolation circuit, the differential gate enable positive terminal P is connected with the positive terminal of the relay coil, the negative terminal of the relay coil is connected with the differential gate enable negative terminal N through the output of the isolation circuit, and the relay coil is powered on to control the relay normally open contact to close the door lock low side and connect the door lock power supply negative pole POW- with the power supply, and the energy storage of the power-off delay circuit is realized;

[0028] The hardware logic controller encodes the states of the first power switch, the second power switch and the relay contact state into an alternating signal and sends the alternating signal to the CPU.

[0029] After the logic control of the CPU according to the gate enable signal after signal conversion, the door opening signal, the door lock state and the encoded first power switch state, the second power switch state and the relay contact state, the unlock controller signal is output, the second power switch is turned on through the isolation circuit, the door lock high side and the door lock power supply positive pole POW+ are connected, and the door lock is powered on and unlocked.

[0030] After the gate enable signal is invalid, the PWM controller is powered off, the first power switch gate is not supplied with power, and the first power switch drain is cut off; the relay normally open contact is disconnected under the action of the power-off delay circuit, the door lock high side and the low side are powered off, and the door lock is locked; the CPU controls the second power switch to be turned off according to the logic requirement, and there is no off timing requirement.

[0031] Further, the hardware logic controller sends a signal for controlling the relay after logic processing according to the received signal input, and does not accept the software instruction of the CPU; the hardware logic controller and the CPU are for one-way signal transmission, and the hardware logic controller encodes the states of Q1, Q2 and K1 and the states of the output signals thereof and sends the alternating signal to the CPU.

[0032] Advantages: compared with the prior art, the advantages of the present application are:

[0033] (1) The PWM controller, the transformer TR1, D1, C1 and R1 form a fail-safe circuit, the gate enable signal is generally a direct current high voltage hard line signal, which cannot directly control the gate of the power switch tube, the fail-safe circuit converts the independent loop and isolated door opening enable hard line signal sent by the upper control system into the gate control signal of the power switch Q1, and any failure of the line, device or combination thereof in the transmission process will lead to no driving voltage of the gate of Q1, Q1 is not conductive, and the power supply for the rear circuit is unavailable.

[0034] (2) hardware logic controller, R5, U2 and the coil of relay K1 constitute a inherent safety fault circuit, the failure of any device or its combination will lead to the normally open contact of relay K1 not closed, which cannot provide power return loop for the low side of door lock.

[0035] (3) two independent inherent safety fault circuits are connected in series, which respectively control the high side and low side of door lock control circuit power supply, and higher level of functional safety can be realized;

[0036] (4) relay K1 is provided with hardware delay opening circuit, through the state feedback of Q1, the hardware logic controller can control the closing and opening of the contact of relay K1B under the condition of no current, prolong the service life of the contact, and effectively avoid the contact sticking, and improve the safety;

[0037] (5) the power supply control of door lock is connected in series by three different physical principle switching devices, which avoids the failure of the same mechanism;

[0038] (6) the power supply (POW+, POW- constitutes a power supply loop) of door lock is an independent isolated power supply, and even if the high side or low side of door lock is short-circuited with other power supply, a closed loop will not be formed, and therefore the door lock will not be unlocked;

[0039] (7) semiconductor switching devices are used to replace multiple relays to realize safety function, and the circuit reliability is good.

[0040] (8) the switching device of door lock power supply control circuit is detected, and has a fault detection function;

[0041] (9) the hardware logic controller uses alternating signal to transmit state information to CPU unidirectionally, including the control command sent by the hardware logic controller, the state of switching device of lock power supply control circuit and the like. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is the structure schematic diagram of safety control circuit of the application;

[0043] Figure 2 is the flow chart of door lock unlocked by power supply;

[0044] Figure 3 is the flow chart of door lock locked by power supply. DETAILED DESCRIPTION

[0045] The application will be described in detail below in combination with the drawings and specific embodiments.

[0046] Working process and principle of the application:

[0047] Before the door is opened, the door lock has no power supply, the door is in the locked state, the superior equipment gives the differential door enable signal, the signal drives the hardware PWM controller to output the pulse signal, drives the isolation transformer to output the pulse signal, and forms the gate drive signal of N-type MOSFET Q1 after rectification and filtering, controls Q1 to be turned on, and the circuit is a self-contained type of fail-safe circuit.

[0048] The normally open contact of the relay K1 controls the low side of the door lock power supply, the coil high side of the relay K1 is powered by the positive end of the door enable signal, and the low side is controlled by the optocoupler. After the hardware logic controller receives the door enable signal from the superior equipment, the enable signal is output to control the optocoupler to drive the relay K1A coil to be powered, the normally open contact K1B is closed, and the door lock low side is connected to the door lock power supply negative pole POW-. This circuit is a self-contained type of fail-safe circuit.

[0049] After the CPU receives the door enable signal and the door opening signal, it outputs the unlock control signal according to the door control logic requirements, controls the P-type MOSFET to be turned on after the optocoupler isolation, and the door lock is powered to be unlocked, and the door can be opened.

[0050] After the door release signal is invalid, the PWM controller is powered off, the gate of Q1 has no power supply, and the drain-source of Q1 is cut off. Since the relay coil K1A is connected in parallel with the power-off delay circuit, the K1B contact is delayed to be opened. At this time, the contact can be opened without current, the high side and the low side of the door lock have been cut off, and the door lock is in a locked state without power. The CPU can control the MOSFET Q2 to be turned off according to the logic requirements, without strict turn-off timing requirements.

[0051] The states of Q1, Q2, and K1 are fed back to the hardware logic controller, and then sent to the CPU through the alternating signal encoder. The CPU diagnoses the states of Q1, Q2, and K1. The hardware logic controller and the CPU are one-way signal transmission.

[0052] Circuit component:

[0053] PWM controller: hardware logic controller, converts differential door enable signal into PWM pulse signal;

[0054] Transformer TR1: signal transformer, outputs pulse signal in proportion to input PWM signal;

[0055] D1, C1: form a rectified and filtered signal, rectify the pulse signal into a stable voltage;

[0056] Q1: N-type MOSFET

[0057] R1: gate discharge resistor of MOSFET Q1, discharges the gate voltage of Q1 after the door enable signal is invalid, so that the drain-source of MOSFET is cut off;

[0058] Signal conversion circuit: convert the differential gate enable signal into a signal recognizable by the CPU and the hardware logic controller;

[0059] U1, R4: isolation circuit of gate control signal of MOSFET Q2;

[0060] R2, R3: gate drive circuit of MOSFET Q2;

[0061] Q2: P-type MOSFET

[0062] Hardware logic controller: a logic controller composed of hardware logic gate array internally, such as CPLD, FPGA;

[0063] U2, R5: isolation circuit of low-side control signal of relay K1 coil K1B;

[0064] K1: electromagnetic relay, composed of coil K1A and normally open and normally closed contact K1B;

[0065] Power-off delay circuit: composed of passive components, stores energy when the gate enable signal is valid and U2 is turned on, releases electrical energy after the gate enable signal is invalid, and supplies power to the relay K1A coil to delay the disconnection of the contact K1B;

[0066] Door lock: the locking device of the door, which is unlocked after power-on and the mechanical device is in the locked position after power-off.

[0067] As shown in Figure 1 , the safety control circuit of the application comprises a first inherent safety circuit, a second inherent safety circuit and an unlocking circuit.

[0068] The first inherent safety circuit comprises a PWM controller, a transformer circuit, a rectifier filter circuit and a first power switch MOSFET. The PWM controller receives a gate enable differential signal (i.e. the differential signal of the gate enable P signal and the gate enable N signal), and outputs a PWM pulse signal after modulation. The transformer circuit is an isolation transformer TR1, which outputs the PWM pulse signal output by the PWM controller in proportion. The rectifier filter circuit is composed of a first diode D1 and a first capacitor C1, which rectifies the proportional pulse signal output by the isolation transformer TR1 into a stable voltage as the gate drive signal of the first power switch MOSFET Q1, controlling the conduction of the first power switch MOSFET Q1. The first power switch MOSFET Q1 is an N-type MOSFET, the gate of which is connected with the rectifier filter circuit, the drain of which is connected with the positive pole POW+ of the door lock power supply, and the source of which is connected with the source of the second power switch MOSFET Q2 of the second inherent safety circuit. The state of the first power switch MOSFET is the output state of the first inherent safety circuit, which is fed back to the hardware logic controller of the second inherent safety circuit.

[0069] Further, the gate of the first power switch MOSFET is also provided with a discharge circuit, which discharges the voltage across the gate of the first power switch after the gate enable signal is disabled, so as to cut off the drain-source of the first power switch. The discharge circuit can be a circuit composed of a transistor, a MOSFET and a resistor, or can be a resistor.

[0070] In the embodiment, the discharge circuit is a first resistor R1, which is a gate discharge resistor of the first power switch MOSFET Q1. After the gate enable signal (i.e. the gate enable P signal and the gate enable N signal) is disabled, the discharge circuit discharges the voltage across the gate of the first power switch MOSFET, so as to cut off the drain-source of the first power switch MOSFET.

[0071] The second inherent formula failsafe circuit includes a hardware logic controller, an isolation circuit, a relay and a power-off delay circuit. The hardware logic controller is a logic controller composed of a hardware logic gate array, such as a CPLD and a FPGA. The gate enable differential signal of the upper device (i.e. the differential signal of the gate enable P signal and the gate enable N signal) is converted into a signal recognizable by the hardware logic controller through a signal conversion circuit. The hardware logic controller receives the converted gate enable differential signal and outputs an enable signal after logic control. The isolation circuit is an isolation circuit of the low side control signal of the relay coil K1A, which includes a fifth resistor R5 and a second optocoupler U2. One end of the fifth resistor is connected with the hardware logic controller, and the other end is connected with the first port of the second optocoupler U2. The second port of the second optocoupler U2 is connected with GND, the third port is connected with the gate enable N signal, and the fourth port is connected with the low side of the relay coil K1A. The relay K1 is an electromagnetic relay, which includes a relay coil K1A and a relay normally open contact K1B. The high side of the relay coil K1A is connected with the gate enable P signal, and the relay normally open contact K1B is connected with the low side of the door lock. When the relay coil K1A is powered, the relay normally open contact K1B is closed, and the low side of the door lock is connected with the negative pole POW- of the door lock power supply. The power-off delay circuit is composed of passive components, stores energy when the gate enable signal is valid and the second optocoupler U2 is turned on, and releases the electric energy to power the relay coil K1A after the gate enable signal is invalid, thereby delaying the disconnection of the relay normally open contact K1B.

[0072] The relay normally open contact K1B controls the low side of the door lock power supply, the high side of the relay coil K1A is powered by the positive terminal of the gate enable signal, and the low side is controlled by the optocoupler. After the hardware logic controller receives the gate enable signal of the upper device, the hardware logic controller outputs an enable signal to control the optocoupler, thereby powering the relay coil K1A, closing the relay normally open contact K1B and connecting the low side of the door lock with the negative pole POW- of the door lock power supply.

[0073] The hardware logic controller sends the states of the first power switch MOSFET Q1, the second power switch MOSFET Q2 and the relay K1 to the CPU through the alternating signal encoder, and the CPU diagnoses the states of the first power switch MOSFET Q1, the second power switch MOSFET Q2 and the relay K1, and the hardware logic controller and the CPU are in one-way signal transmission.

[0074] The unlocking circuit comprises the CPU, a second power switch MOSFET isolation circuit, a driving circuit and the second power switch MOSFET Q2. The second power switch MOSFET isolation circuit is a gate control signal isolation circuit of the second power switch MOSFET Q2, comprising a fourth resistor R4 and a first optocoupler U1. One end of the fourth resistor R4 is connected with the CPU output, and the other end is connected with the first port of the first optocoupler U1. The second port of the first optocoupler U1 is connected with GND, the third port is connected with one end of a third resistor R3 of the driving circuit, and the fourth port is connected with the negative pole POW- of the door lock power supply. The driving circuit is a gate driving circuit of the second power switch MOSFET Q2, comprising a second resistor R2 and the third resistor R3. One end of the second resistor R2 is connected with the gate of the second power switch MOSFET Q2, and the other end is connected with the source of the second power switch MOSFET Q2. The other end of the third resistor R3 is connected with the gate of the second power switch MOSFET Q2. The second power switch MOSFET Q2 is a P-type MOSFET. The source of the second power switch MOSFET Q2 is connected with the source of the first power switch MOSFET Q1, and the drain of the second power switch MOSFET Q2 is connected with the high side of the door lock. The state of the second power switch MOSFET is fed back to the hardware logic controller of the second inherent type safety circuit as the state of the unlocking circuit.

[0075] After the CPU receives the converted differential door enable signal, the door opening signal, the door lock state and the numbered first power switch MOSFET state, the second power switch MOSFET state and the relay K1 state, according to the door control logic requirement, the unlocking control signal is outputted, and after the light coupling isolation, the P-type MOSFET is turned on, the door lock is powered and unlocked, and the door can be opened.

[0076] After the door enable signal is disabled, the PWM controller is powered off, the first power switch MOSFET Q1 gate has no power supply, the first power switch MOSFET Q1 drain-source is cut off, and since the relay coil K1A is connected in parallel with the power-off delay circuit, the relay normally open contact K1B is delayed to be opened, at this time, the relay normally open contact K1B can be opened without current, the high side and the low side of the door lock have been cut off, and the door lock is in a power-off locking state; the CPU can control the second power switch MOSFET Q2 to be turned off according to the logic requirement, and there is no strict turn-off timing requirement.

[0077] The door lock power supply can adopt a completely independent isolation power supply to form an independent power supply loop from POW+ to POW-, and the first power switch, the second power switch and the relay in the loop can adopt MOSFET, IGBT or other types of switching elements.

[0078] The door lock is a locking device of a door, which is unlocked after being powered on and is in a locking position after power-off.

[0079] As shown in Figure 2 , Figure 3 , a safety control circuit control method of the present application comprises the following steps:

[0080] The positive end P and the negative end N of the differential door enable signal are input into the first inherent type fault safety circuit, the second inherent type fault safety circuit and the unlocking circuit;

[0081] The first inherent type fault safety circuit modulates, transforms and rectifies and filters the differential door enable signal, and outputs the rectified and filtered signal, which drives the first power switch to be turned on, connects the door lock power supply positive pole POW+ and feeds back the output state of the first inherent type fault safety circuit to the second inherent type fault safety circuit;

[0082] The second inherent type fault safety circuit encodes the output state of the first inherent type fault safety circuit, the unlocking circuit state and its own state into an alternating signal and sends the alternating signal to the unlocking circuit through a hardware logic controller; at the same time, the second inherent type fault safety circuit performs logic control on the differential door enable signal, the door opening signal, the door lock state, the first inherent type fault safety circuit output state, the unlocking circuit state and its own state after signal conversion, and drives the door lock low side and the door lock power supply negative pole POW- to be connected through an optical coupling isolation;

[0083] The unlocking circuit performs logical control according to the encoded first inherent safety circuit output state, the unlocking circuit state and the second inherent safety circuit output state, the received signal-converted differential gate enable signal, the door opening signal and the door lock state, and outputs an unlocking controller signal to control the door lock high side to be connected to the door lock power supply positive pole POW+ through optical coupling isolation; and then the door lock is powered on and unlocked;

[0084] After the differential gate enable signal is invalid, the door lock high side is disconnected from the door lock power supply positive pole POW+, the door lock low side is disconnected from the door lock power supply negative pole POW- in a delay manner, and the door lock is in a power-off locking state.

[0085] The control method specifically comprises the following steps:

[0086] The differential gate enable signal drives a PWM controller to output a pulse signal, the pulse signal drives an isolation transformer to output a pulse signal, the pulse signal output by the transformer is rectified and filtered to obtain a gate drive signal of a first power switch, and then the first power switch is controlled to be turned on, so that the source of the first power switch is connected to the door lock power supply positive pole POW+.

[0087] Synchronously, the differential gate enable signal is input to a hardware logic controller after signal conversion, the hardware logic controller processes the signal-converted differential signal, outputs a control signal to the input end of an isolation circuit, the positive end P of the differential gate enable signal is connected to the positive end of a relay coil, the negative end N of the differential gate enable signal is connected to the output of the isolation circuit through the negative end of the relay coil, the relay coil is powered on, and the normally open contact of the relay is closed to connect the door lock low side to the door lock power supply negative pole POW-; and the energy storage of a power-off delay circuit is simultaneously started.

[0088] The hardware logic controller encodes the states of the first power switch, the second power switch and the relay contact into an alternating signal and sends the alternating signal to a CPU.

[0089] The CPU performs logical control according to the signal-converted gate enable signal, the door opening signal, the door lock state, the encoded first power switch state, the second power switch state and the relay contact state, and outputs an unlocking controller signal to control the second power switch to be turned on through the isolation circuit, so that the door lock high side is connected to the door lock power supply positive pole POW+ and the door lock is powered on and unlocked.

[0090] After the gate enable signal is invalid, the PWM controller is powered off, the gate of the first power switch is not supplied with power, and the drain of the first power switch is cut off; the normally open contact of the relay is disconnected in a delay manner under the action of the power-off delay circuit, the door lock high side and the door lock low side are both powered off, and the door lock is locked.

[0091] After the door enable signal is invalid, the CPU controls the second power switch MOSFET to be turned off according to logic requirements, and there is no turn-off timing requirement.

[0092] The hardware logic controller sends a signal to control the relay after logic processing according to the signal input received by itself, and does not accept software instructions of the CPU. There is one-way signal transmission between the hardware logic controller and the CPU. The hardware logic controller encodes the states of Q1, Q2, K1 and the states of its own output signals and sends them to the CPU as alternating signals.

Claims

1. A safety control circuit, characterized by, The application relates to a safety circuit for a door lock, which comprises a first inherent safety circuit, a second inherent safety circuit and an unlocking circuit. The input of the first inherent safety circuit is a differential door enable signal, which controls the on-off of a first power switch, the input end of the first power switch is connected with a door lock power supply positive pole POW+, the output end is connected with the positive pole of the unlocking circuit, and the state of the first power switch is fed back to the control end of the second inherent safety circuit and the door lock unlocking circuit. The input of the second inherent safety circuit comprises a signal-converted differential door enable signal, a door opening signal, a door lock state, the state of the first power switch of the first inherent safety circuit, the state of the unlocking circuit and the state of the second inherent safety circuit, the output state of the first power switch of the first inherent safety circuit, the state of the unlocking circuit and the state of the second inherent safety circuit are sent to the unlocking circuit through an alternating signal encoder; the second inherent safety circuit controls a relay contact, which is connected with a door lock low side and a door lock power supply negative pole POW-. The input of the unlocking circuit comprises a signal-converted differential door enable signal, a door opening signal and a door lock state, the unlocking circuit outputs an unlocking control signal according to the encoded output state of the first inherent safety circuit, the state of the unlocking circuit and the state of the second inherent safety circuit sent by the second inherent safety circuit, controls the opening of a second power switch and realizes safe unlocking. The first inherent safety circuit comprises a PWM controller, a voltage transformation circuit, a rectification filter circuit and a first power switch, the input of the PWM controller is a differential door enable signal, the output is a gate drive signal of the first power switch through the voltage transformation circuit and the rectification filter circuit, the source of the first power switch is connected with the unlocking circuit, the drain of the first power switch is connected with the door lock power supply positive pole POW+, and the state of the first power switch is fed back to the second inherent safety circuit as the output state of the first inherent safety circuit.

2. A safety control circuit according to claim 1, characterized in that The first inherent safety circuit further comprises a discharging circuit arranged at the gate of the first power switch, which discharges the voltage between the gate of the first power switch after the door enable signal is disabled, so that the drain-source of the first power switch is cut off.

3. A safety control circuit according to claim 2, characterized in that The second inherent safety circuit comprises a hardware logic controller, an isolation circuit, a relay and a power-off delay circuit, the input of the hardware logic controller comprises a signal-converted differential door enable signal, a door opening signal, a door lock state, the output state of the first inherent safety circuit, the state of the unlocking circuit and the state of the relay, one output end of the hardware logic controller is connected with the unlocking circuit, the other output end is connected with the isolation circuit, the other end of the isolation circuit is connected with the relay, the relay is connected with the power-off delay circuit in parallel, the other end of the relay is connected with the door lock low side and controls the communication between the door lock low side and the door lock power supply negative pole POW-, and the state of the relay is fed back to the hardware logic controller as the output state of the second inherent safety circuit.

4. A safety control circuit according to claim 1, characterized in that ​ 5. A safety control circuit according to claim 4, characterized in that The isolation circuit comprises a fifth resistor and a second optocoupler, the relay comprises a relay coil and a relay normally open contact, the first port of the second optocoupler is connected with the hardware logic controller through the fifth resistor, the second port is connected with GND, the third port is connected with the gate enable N signal, and the fourth port is connected with the relay coil low side; the relay coil high side is connected with the gate enable P signal, the relay normally open contact is connected with the door lock low side, and the door lock low side is connected with the door lock power supply negative pole POW- when the relay coil is powered.

6. A safety control circuit according to claim 1, characterized in that The unlocking circuit comprises a CPU, a second power switch isolation circuit, a driving circuit and a second power switch, the input of the CPU comprises the differential gate enable signal after signal conversion, the door opening signal, the door lock state, the output state of the first power switch of the first inherent safety circuit after numbering, the unlocking circuit state and the relay contact state of the second inherent safety circuit, the output of the CPU is connected with the second power switch isolation circuit, the other end of the second power switch isolation circuit is connected with the driving circuit, the driving circuit is connected with the gate and the source of the second power switch, the source of the second power switch is connected with the first inherent safety circuit, the drain of the second power switch is connected with the door lock high side, and the state of the second power switch is fed back to the second inherent safety circuit as the unlocking circuit state.

7. A safety control circuit according to claim 6, characterised in that, The second power switch isolation circuit comprises a fourth resistor and a first optocoupler, the driving circuit comprises a second resistor and a third resistor, the first port of the first optocoupler is connected with the CPU through the fourth resistor, the second port is connected with GND, the third port is connected with one end of the third resistor of the driving circuit, and the fourth port is connected with the door lock power supply negative pole POW-. One end of the second resistor of the driving circuit is connected with the gate of the second power switch, the other end is connected with the source of the second power switch, and the other end of the third resistor is connected with the gate of the second power switch.

8. The safety control circuit according to claim 1, wherein the door lock power supply is an independent isolation power supply, and an independent power supply loop is formed from POW+ to POW-. The first power switch, the second power switch and the relay in the loop are MOSFET, IGBT or triode.

9. A safety control circuit control method characterized by, The steps comprise: The positive end P and the negative end N of the differential gate enable signal are input into the first inherent safety circuit, the second inherent safety circuit and the unlocking circuit; The first inherent safety circuit modulates, transforms and rectifies and filters the differential gate enable signal, and outputs the rectified and filtered signal, the signal drives the first power switch to be turned on, the first inherent safety circuit is connected with the door lock power supply positive pole POW+, and the output state of the first inherent safety circuit is fed back to the second inherent safety circuit; The second inherent safety circuit encodes the output state of the first inherent safety circuit, the state of the unlocking circuit and its own state into an alternating signal through a hardware logic controller and sends the signal to the unlocking circuit; at the same time, the second inherent safety circuit performs logic control on the differential gate enable signal after signal conversion, the door opening signal, the door lock state, the output state of the first inherent safety circuit, the state of the unlocking circuit and its own state, and then drives the door lock low side and the negative pole POW- of the door lock power supply to be connected through an optical coupling isolation; The unlocking circuit performs logic control on the encoded first inherent safety circuit output state, the unlocking circuit state and the second inherent safety circuit output state, and the received differential gate enable signal after signal conversion, and the door opening signal and the door lock state, and outputs an unlocking controller signal to control the door lock high side and the positive pole POW+ of the door lock power supply to be connected through an optical coupling isolation; and then the door lock is unlocked after being powered on. After the differential gate enable signal is invalid, the door lock high side and the positive pole POW+ of the door lock power supply are disconnected, the door lock low side and the negative pole POW- of the door lock power supply are disconnected after a time delay, and the door lock is in a power-off locking state.

10. The method of claim 9, wherein the safety control circuit is configured to: The control method specifically comprises the following steps: The differential gate enable signal drives a PWM controller to output a pulse signal, the pulse signal drives an isolation transformer to output a pulse signal, the pulse signal output by the transformer is rectified and filtered to obtain a gate drive signal of a first power switch, and then the first power switch is controlled to be turned on, so that the source of the first power switch and the positive pole POW+ of the door lock power supply are connected; Synchronously, the differential gate enable signal is input to a hardware logic controller after signal conversion, the hardware logic controller processes the differential signal after signal conversion, outputs a control signal to the input end of an isolation circuit, the positive end P of the differential gate enable signal is connected to the positive end of a relay coil, and the negative end N of the differential gate enable signal is connected to the output of the isolation circuit through the negative end of the relay coil, so as to control the relay coil to be powered on, the normally open contact of the relay is closed to connect the door lock low side and the negative pole POW- of the door lock power supply, and the energy storage of a power-off time delay circuit is simultaneously controlled; The hardware logic controller encodes the states of the first power switch, the second power switch and the relay contact and the states of the output signals of the hardware logic controller to an alternating signal and sends the signal to a CPU; The CPU performs logic control on the differential gate enable signal after signal conversion, the door opening signal, the door lock state, the encoded first power switch state, the second power switch state and the relay contact state, and then outputs an unlocking controller signal to control the second power switch to be turned on through an isolation circuit, so that the door lock high side and the positive pole POW+ of the door lock power supply are connected, and the door lock is unlocked after being powered on; After the differential gate enable signal is invalid, the PWM controller is powered off, the gate of the first power switch is not supplied with power, and the drain of the first power switch is cut off; the normally open contact of the relay is disconnected after a time delay under the action of the power-off time delay circuit, the door lock high side and the low side are both powered off, and the door lock is locked; the CPU controls the second power switch to be turned off according to the logic requirement, and there is no requirement for the turn-off time sequence.

11. The method of claim 9, wherein the safety control circuit is configured to: The hardware logic controller sends out the signal of controlling the relay after logic processing according to the signal input received by itself, and does not accept the software instruction of the CPU; the hardware logic controller and the CPU are for one-way signal transmission, and the hardware logic controller sends the state of Q1, Q2 and K1 and the state of its own output signal to the CPU after coding as an alternating signal.

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